Automatic control for fuel mixing devices



Marh22,193s.f W'GROH 2,111,855

AUTOMATIC CONTROL FOR FUL MIXING DEVICES Filed Dec. 3, 195e 7 11g/fred5,04.

Patented Mar. 22, 1938 N UNlTEosTATEs PATENT OFFICE 2,111,855l AUTOMATICCONTROL FOR FUEL MIXING DEVICES Wilfred Groh, Gravenhurst, Ontario,Canada Application December 3, 1936, Serial No. 113,967 Y,

' 12 claims.V (o1. 137-104) This invention'relates to improvements incarburetors or fuel mixing `devices and more particularly to means forthermostatically'controlling the ratio of fuel and `air in accordancewith prevailing atmospheric temperatures.'

The principal object of vthis invention is to provide an improved formof mechanism which Vwill automatically control the level of the fuel `intheiioat chamber in relation to- "the fuel jet or jets in response tochanges in atmospheric temperatures and to provide a formof device Aforthis purpose which will function in a dependable manner and will not besubjected to detrimental hammering or vibratory actions whenl associatedwith a fuel feed supply of the widely used pulsating p-ump type. v

The principal feature of the invention resides inthe novel' constructionandarrangement of parts Awherebythe valve means supplying fuel to theVfloat bowl or chamber Vis Ythermostatically shifted in relation to thecontrolling float to regu- Alate the height at which the floatwillvclosevthe supply valve. Y i i Figure 1 is a mid-sectionalelevational View of acontrolmechanism constructed in accordance with thepresent invention and incorporated -in a carburetor structure. f frFigure 2 is a fragmentary sectional `view showing a modified arrangementof fuel circulating passages. I p Y Itis extremely desirable,particularly inthe operation of combustion engines of motor cars, toensure 4a constant ratio of fuel and air being fedto' the engineirrespective of the wide-variations encountered in atmospherictemperatures.

This problem has been recognized for sometime 4and various means havebeen proposed in order to overcomethe diicultywith varying degrees ofsuccess. ,Y

It has been previously proposed toprovide thermostaticmeans forrautomatically adjusting the choke to regulate the volume of air enteringthe engine and it has also been proposed to f thermostatically regulatethe actual volume of fuel entering the jet of the-carburetor, but so faras I am aware I am the firstto propose a means whereby the actuallevelof the fuel in the carburetor bowl or chamber is automaticallyregulated in accordance with prevailing temperatures asV a means ofincreasing or diminishing the amount of fuel drawn from the jet or jetsin the operation of the engine. Y

While my invention is capable of Wide struc- `tural variation andadaptation, I have shown for purposes of illustration a simple form ofapparatus constructed-in accordance with the presentinventionandreferring to this illustrated construction, the floatchamber I is shown provided with the usual fuel outlet 2 for conductingfuel to the jetor jets 3, which jet is shown disposed in lthe suctionconduit 4 of the carburetor and encircled by a Venturi tube 5, the usualthrottle being shown for controlling the volume of the `mixture passingtothe engine. Y

A cover member 'I is fitted to the upper end of the float chamber I andhas a central opening in which a guide block 8 is seated and suitablysecured in place, a vertical vguide bore 9J being provided therein forslidably receiving and'guiding a displaceable tube member IIJ.

The upper end of the block is provided with a'circular threaded flange II to which an inverted cup-shaped housing I2 is threadedly secured,thereby forming a chamber above the block 8 into'.y which the upperendof the tube I0 extends.

"A `bellowsmember I3 here shown of deeply corrugatedform has .the upperend closed and :operatively secured to the upper extremity. of the tubeI0 and the lower end of the bellows is suitably sealed to the flange IIpreferably by-being `soldered into a groove therein as shown at I4.

The space between the element I3` and the casing I2 forms a chamber I5,which, according to `the present invention, I propose to fill, with.mercury,valcoliol or any other suitable fluid medium `having thedesired characteristics of eX- pansion and contraction in response totemperature changes' and this fluid medium may be introduced'through theopening I6 in the top 'which will then be sealed by a suitablescrew'plug IT.

I preferably completelyll the chamber I5 to the exclusion of all air sothat any expansion of the fluid'medium will effect a positive and non-'yielding' downward displacement of the tube I0 `:and such llingpreferably is accomplished with the fluid medium at atemperature*substantially corresponding to the temperature'V of thesurrounding atmosphere and that ofthe structure.

The housing I2 is here shown provided with heat exchange finsadapted tocontact extensively with the vatmosphere as a means of encour- [agingthe conduction of heat to and from the atmosphere and the fluid mediumin the chamber I5', and as a means of changing the actual volumetriccapacity of the chamber I5, I have shown fa rubber or other resilientsealing ring I2 interposed between the flange II and bottom of thecylindrical housing I2 which will retain an effective seal at thispoint, while permitting threaded adjustingthe casing I2 totherebyeii'ect changes Yand. associated parts.

in the volume of the chamber I5 as a means of effecting an adjustment ofthe vertical positioning of the tube I0.

A fuel supply tube I8 directs fuel into a vertical passage I9 in theblock 8, which passage leads upwardly into the interior of the bellowsI3 and downwardly into the interior of a second and smaller bellows 2U,which is here shown sealed at its upper end to the lower flange II ofthe block, while The lower end of the bellows 20 has the tube Iextending therethrough and sealed thereto as indicated at 2|.

The fuel thus entering the lower bellows 20 is allowed to pass into thetube I0 by way of the ports 22 therein and the fuel flows from the lowerend of the tube I0 in a controlled manner as hereinafter defined.

'Ihe lower end of the tube I Il has mounted thereon a sleeve 23 havingradially disposed toggle arms 24 pivotally connected therewith at 25.

A semi-circular stirrup 26 preferably of a resilient nature, ispivotally linked at its end to the toggle members 24 as indicated at 21and this stirrup element extends down directly below the bottomextremity of the tube I0 and carries a needle valve 28 which cooperatesdirectly with a valve seat 29 arranged in the lower extremity of thetube.

The outer ends of the toggle member 24 are adapted to rest directly onthe float I so that as the fuel level rises in the float chamber thearms 24 will be swung upwardly on their pivots 25 so that the springstirrup 26 will move the valve 28 to close the outlet from the tube Illand with the parts in the position slown it is assumed that the fuellevel is at a mean height indicated by the letter n and the prevailingtemperature may be assumed to be say, 40 F.

Assuming now that a considerably lower tem- -perature is encountered,then there will be a resultant contraction of the fluid medium in thechamber I causing an upward lift on the tube I0 unsealing the lower endthereof from the valve 28 and allowing fuel to flow into the floatchamber until the float again raises sufliciently to close the valve 28,thereby raising the fuel level, for example, to the line c.

If, on the other hand, an increase in temperature in the atmosphere isencountered above normal, then there will be a resultant expansion ofthe fluid medium in the chamber I5, thereby forcing the tube I0downwardly to cause the valve 28 to close with a lower float position,so that the fuel level will approximate that indicated by the letter h.

After careful experimentation I have found that by controlling theactual fuel level in the float chamber a proportionate increase ordecrease in the amount of fuel drawn from the jet 3 results, so that thefuel air mixture passing to the engine may be accurately regulated.

Moreover it will be observed that the pressure of the fuel supplyentering the port or passage I9 will be impressed with somewhat greaterupward force on the tube IU due to the greater end area presented by theupper bellows I3 relative to that presented by the lower bellows 20 andthis effectively offsets the weight of the tube I0 When fuel is fed tothe passage I9 in a pulsating manner it will be seen that this pressurewill be distributed upwardly and downwardly into the respective bellowsand this in conjunction with the weight of fuel resting in the lowerbellows 20 will effect a substantially balanced condition and it is tobe further observed that with the chamber I5 completely filled with aliquid expansion medium, this will effectively offset any inclinationfor the tube I0 to be vibrated or pulsated axially, so that detrimentalvibration will not be imparted to the parts suspended on the lower endthereof, which would tend to interfere with the positive positioning andheating of the cooperating elements, producing wear and strain on theparts.

It will also be observed that any air or vapor trapped in the upper endof the bellows I3 and tube I0 will/act as a cushioning medium,effectively absorbing or damping out the pulsating surges of the fuel asit is fed to the carburetor.

The fuel entering the upper bellows I3 will have a heat exchangerelation to the fiuid medium in the chamber I5 through the metallicbellows I3 and will therefore have a controlling effect on thepositioning of the tube I0 as will be readily appreciated and in Figure2 I have provided for a positive circulation of the fuel through theupper bellows I3 by way of the passage I9 and a passage I 9" conductsthe fuel from the upper bellows I3 to the lower bellows 20. v

What I claim as my invention is:-

1. The combination with a fuel mixing device having a fuel supplychamber and a jet or jets supplied thereby and a fuel supply linethrough which fuel is adapted to be supplied under pressure, of meansfor automatically regulating the level of the fuel in said chambersupply relative to the jet or jets in accordance with changes inatmospheric temperatures, said means including an expansile chamber inpressure communication with the interior of said fuel line, and meansfor restricting displacement of said expansile chamber due to the fuelpressure thereon.

2. The combination with a fuel mixing device having a float chamber forsupplying fuel thereto at a predetermined level and a fuel supply linethrough which fuel is adapted to be supplied under pressure, of meansfor automatically varying the effective fuel level in said float chamberin accordance with changes in atmospheric conditions, said meansincluding a pair of pressureresponsive bellows arranged in oppositionhaving their interiors connected together and to the interior of saidfuel supply line.

3. Means as claimed in claim 2 in which said automatic means includes afloat-controlled valve means for controlling entry of the fuel into saidfloat chamber, said valve means having a common operative connectionwith said pressure-responsive bellows and adjustably supported therebyfor positioning said valve means relative to the float.

4. In a fuel mixing device, a fuel supply chamber for feeding saiddevice, a float in said chamber, a valve structure operativelyassociated with said float including a part displaceable to control theentry of fuel into said chamber, thermostatically responsive means forbodily shifting Isaid part of the valve structure relative to a secondpart thereof and to said float to regulate the effective level of thefuel in said chamber, said thermostatically responsive means comprisinga pressure responsive member separate from said float and operativelyconnected with said displaceable valve part, a fuel supply line throughwhich fuel is adapted to be supplied, under pressure, and pressureresponsive means directly connected with the fuel line for pressureactuation by the fuel and operatively associated with said displaceablevalve part to influence the thermo- 5. Means as claimed in claim 4 inwhich said displaceable valve part includes a fuel supply tubecommunicating with said fuel line and axially displaceable toward andaway from said float and having the displaceable valve part mountedthereon for co-operation with said second valve part, said second valvepart being operatively connected with said float.

6. In a fuel mixing device for combustion engines, a fuel supply chamberhaving a float therein, a fuel supply tube axially slidable toward andfrom said float, means forming a pressure chamber into which said tubeextends, a pressure responsive bellows in said chamber operativelyconnected with said tube, an expansile fluid surrounding said bellowsand filling `said pressure chamber, and fuel control means operativelyinterposed between the said tube and float for controlling the entry offuel into saidfuel supply chamber.

'7. Means as claimed in claim 6 in which means is provided for adjustingthe volumetric capacity of said pressure chamber to adjust the axialposition of said tube.

8. Means as claimed in claim 6 in which the means forming said pressurechamber includes a cup-shaped housing having a threaded connection witha fixed part of the device, a compression seal being interposed betweensaid housing and fixed part to maintain a seal therebetween whilepermitting threaded adjustment of the housing whereby adjustment of thesaid tube is provided for.

9. In a fuel mixing device, a float chamber, a float in said chamber, atube axially slidable having a valve seat adjacent said float, means fordirecting a supply of fuel into said tube, a valve co-operating withsaid valve seat, toggle members mounted on said tube and operativelyengaged by said float, means operatively connecting said toggle meanswith said valve member, and pressure responsive means operativelyconnected with said slidable tube for axially positioning the same, saidtube being slidably mounted in a guide block and the means forconducting fuel to said tube including a bellows sealed at one end tothe tube and at the other end to said guide block, said bellows formingVa receptacle for the fuel supply and said tube having ports leadingtherefrom to the oat chamber.

l0. In a fuel mixing device, a float chamber, a float in said chamber, atube axially slidable having a valve seat adjacent said float, means fordirecting a supply of fuel into said tube, a valve co-operating withsaid valve seat, toggle members mounted on said tube and operativelyengaged by said float, means operatively connecting said toggle meanswith said valve member, and pressure responsive means operativelyconnected with said slidable tube for axially positioning the same, saidpressure responsive means comprising a bellows operatively connectedwith said tube and having its interior open to the fuel supply.

11. In a fuel mixing device, a float chamber, a float in said chamber, atube axially slidable having a valve seat adjacent said float, means fordirecting a supply of fuel into said tube, a valve (zc-operating withsaid valve seat, toggle members mounted on said tube and operativelyengaged by said float, means operatively connecting said toggle meanswith said valve member, and pressure responsive means operativelyconnected with said slidable tube for axially positioning the same, themeans for operatively connecting the toggle arms with the valve membercomprising a spring stirrup member of bowed form having the endspivotally linked to the respective toggle arms.

12. In a fuel mixing device, a float chamber, a float in said chamber, atube axially slidable having a valve seat adjacent said float, means fordirecting a supply of fuel into said tube, a valve co-operating withsaid valve seat, toggle members mounted on said tube and operativelyengaged by said float, means operatively connecting said toggle meanswith said valve member, and pressure Y responsive means operativelyconnected with said slidable tube for axially positioning the same, saidtube being slidably mounted in a guide block and the means forconducting fuel to said tube including a bellows sealed at one end tothe tube and at the other end to said guide block, said bellows forminga receptacle for the fuel supply and said tube having ports leadingtherefrom, said pressure responsive means including a second bellows,means directing the fuel supply first into said second bellows in heatexchange contact therewith, and means conducting the fuel from saidsecond bellows to the interior of said firstmentioned bellows.

WILFRED GROH.

